1. Field of the Invention
The present invention relates to a one-piece food container, particularly to one that has a surface around the edge of the outer rim thereof for a pre-determined sealing film to be heat-sealed thereon in order to form an irreversible tear-off structure, and when the outer rim edge is torn off, the sealing film would not detach from it, providing a reusable and tamper-proof sealed cover for the container.
2. Description of the Related Art
Plastic containers made by vacuum molding have different shapes like boxes, cups and bowls since the amount of materials needed for manufacturing is little; therefore they are suitable for preserving food. However, non-solid food such as jelly, puddings and panna cotta may leak or seep through during transportation and moving. In order to prevent from leakage or seepage, the containers must be completely sealed.
FIG. 1 is a conventional food container with a sealed cover 10. It has liquid food 12 therein and a sealing film or aluminum foil sheet 13 sealed thereon. Such structure can indeed prevent from leakage during transportation and moving of the goods, but after the sealing film or aluminum foil sheet 13 is torn off, the container 11 is no longer available for sealed preservation. FIG. 2 is a conventional food container with a detachable lid 20 disclosed in U.S. Pat. No. 6,168,044. It comprises a bowl 21 and at least one selectively detachable snap 23 on a lid 22. A distinct clicking sound can be heard when combining the bowl 21 and the lid 22, forming a reusable structure. Nevertheless, the invention itself still cannot provide any tamper-proof function and therefore needs extra package to complement the concern; and the extra materials, volumes and weight for the complementary package would cause an increase of costs in transportation, preservation, working personnel, and facilities. Also, it does no good to the environment either. On the other hand, the lid 22 is made by hard materials and is difficult for related information of the food to be printed on. Thus, an extra step of adhering stickers is necessary in the manufacturing process, causing other inconveniences and increasing of costs as well.
In summary, the defect of the food container with a sealed cover 10 can be overcome by the structure of the food container with a detachable lid 20 and vice versa; however, the advantages of both cannot be combined and embodied in one single food container. Therefore, there is still room for improvements.